Ductile tubing connector



Aug. 27, 1946. R. E. SNYDER 8 DUCTILE TUBING CONNECTOR Filed March 15, 1943 rr g :17 H5 he E- Pl'lJ- 96 94 INVENTOR.

=97 95 OBERT ESNYDER I ATTORNEY Patented Aug. 27, 1946 UNITED STATES PATENT OFFICE 2,406,478 DUCTILE TUBING CONNECTOR Robert E. Snyder, Pasadena, Calif.

. Application March 15, 1943, Serial No. 479,247 3 Claims. (01. 285--90) This invention relates to pipe joints or couplings, and more particularly to couplings of the type used to interconnect flexible or yielding pipe through the expedient of a thimble or ferrule freely revoluble upon one of the tubes to beinterconnected and adapted to be engaged upon the other by means of screw threads formed on the thimble and thus join the two tubes in a leakproof connection having sufiicient strength to meet commercial requirements.

In particular, the invention is concerned with the provision of auxiliary resilient means in conjunction With a tubing connector for yieldingly supporting the tubing adjacent its point of entry into the connector. The auxiliary means forms a contracted throat of smaller size than the tubing which may be expanded to fit the size of the tubing through spreading of the parts of the auxiliary structure. The present application is a continuation-in-part of my earlier pending application, Serial No. 326,699, filed March 29, 1940, and in addition to embodying the features of Y such prior application, the present invention incorporates additional features relating to the cross-sectional contour of the interior of the auxiliary structure in its contracted and expanded positions in relation to the contour of the tubing. It is readily apparent that when couplings of the type indicated are used to interconnect sections of tubing, the cross-sectional area of the couplings will be relatively great compared with that of the tubing they serve to interconnect. Furthermore, the connectors being of greater diameter than the tubing on which they are mounted, they are materially stiffer than the tubing. As a result, whenever such a line of tubing is subjected to continued vibration of .flexure, or both, very characteristic points of failure develop in the tubing. In general, these failures occur very close to the juncture of the tubing and the coupling; the exact point of failure depending upon the type of connector used, the type and physical uniformity of the tubing, the vibrational frequency and amplitude, the damping means used, the unsupported length of tube, and other variables. In the greater number of examples, the failure occurs less than one diameter of the enclosed tube away from the coupling or last point of support of the tubing by the coupling.

Scientifically, the explanation may be made in terms of stiffness. Stiffness, according to one authority, is defined as the resistance to deformation under stress, or the restoring force per unit displacement, wherein the deformation is presumed not to exceed. the elastic limit of the material under consideration (Eshbach). Thus inatrain of directly connected members of differing individual stiffnesses, the resistanceto deformation or the restoring force per unit displacement will vary from member to member. The general rule seems to hold that under vibrational or cyclical stresses, stress concentrations will be produced in the train at all junctures of members of differing stiffnesses.

In .a tube subjected to repeated fiexure, either cyclical or otherwise, each unit particle of the material of whichv the tube is composed, is subjected alternately to tension and compression stresses, thisaction being most pronounced near the outer surface of the tube. The particles are, therefore, alternately pulled apart and pressed toward each other, and, as such action continues,

they become displaced with reference to each other within thestructure of the material, and gradually produce a surface waviness on the tube. These waves usually appear on circumferential arcs about the tube, and continued fiexure tends to deepen the wave troughs until fissures occur at the bottoms of the troughs, which fissures gradually increase in length and width, ultimately uniting with other fissures, and a circumferential plane of weakness begins to develop. The resultant decrease in stiffness of the tubing along this plane causes a corresponding increase in the stress concentration in the weak portion and further hastens the action. When the fissure finally works clear through the tube, the process of progressive failure is complete. Any local corrosion may itself be the cause of a fissure or may aid in deepening a fissure as the oxide products created in the fissure act as a wedge to deepen it still further under continued fiexure.

As an example, when a brass coupling is attached to a ductile copper tube in accordance with conventional practice, a construction is presented wherein a length of tubing consists of portions immediately adjacent each other and of different cross sectional area and hence possessing difierent degrees of stiffness, the portion having the lesser cross sectional area v the more flexible of the two. It is well known, however, that whenever a member of such a character is subjected to repeated flexure, a concentration of stress will be imposed upon the por-' tion of lesser stiffness, immediately adjacent the point of its last support by the stifier of the two portions; This accounts for the well recognized fact that the point of most probable failure of a conventional ductile copper tube, such as those usually being means are 7 jected to repeat flexure.

A more detailed object in this connection is to avoid the concentration of stress-referred to by providing means for distributing stresswhich inevitably occurs when fiexure "a: "thetubirig occurs.

Inasmuch as it is out 'of the duesticin Y to preventthe development of such stress {my 7 present invention seeks to make the stress innoc uous insofar as damage to the tubing is conearned; and this can best be 'a'ccomplished by "effecting ''the distribution of the -stress "over a mat n gthpf th'e tubin-g; and thus avoidfthe 6o -tration of-stress a single point which hreteforehas been the direct cause- "of failure 'in' ductile -copper tubing subject to re'peated 'fikure, r 1 w, I A furth cr object of the present inventioh is-to assure the distribution of "stress referred to 3 by 'ineans'ef a-yielding resilint support for the more flexible otwo portions f the conductor, preferably i carried by "the stiifer -of the two and extending thelefroinin 1 continuous Contact with 'the more *fli'zible member 1 in such 'a' manner as to tta'in-t1ieresults desired. Other manners of a reaching the Iproblem and providing the disttibiition of "stress *by means of "different types of support io'r the less stiff member, "form the subject 'in'atter of United States Letters Patent No. 252711502, issued January "27, 1942, and No. 2, 7S0, iSSlled k [aich -16, 1943.

'Ahothi cot of 1113 invention is to provide means fe'sili'ently sup orting thefinore flexible of the two po rtions of -*the *con'ductor, which "carried by the 's'tifie'r member and engagefthe m'cre fi'eX-ible meirnber in a sliding engagement, the reby e'nhancin'g the degree of flexibility-of the aissembled unit.

Anotn'er obj ect of my invention is the provision of stress-disti ibuting m'eans for 1 use in conjunction "with the coupling for ductile met'al tubing iii-the manner indicated, which interferes" in no irianner wriat'soever with the 'efliciency of the coupling m'emb'er "as 's uch, --'does not addmaterially to 1 its costv of manufacture, Sand does I not complicate'or make 'more diflilcult the installation and/or'servi'cin'g 0f the coupling "member. A further object is the provision of means-"for avoidingfconcentration of stress in "a ductile metal tubing adj acentlthe couplings used in connectio'n'with: that tubing, which :d'oes'not detract materially from thafiex'ibility of the tubing considere'das' a" whole.

Yet-another object of=my inventionisthe'provision of .:means *for distributing stress over a 'malterial -length'of tubing adjacent'the coupling used -'in connection with that tubing, which distributing means is constructed entirely of fir'eproof and heat-resistant materiaL preferably of I thesame materialas that of which' thecoupling member is cons'tructed; and adapted't'o lend itself economically "to large-scale 'pro'duction upon 'a quantity basis by automatic machinery. 5

In-' addition to Y the fore'g'oihg general objects it i's 'a further particular object of m'y invention to provide resilient means adapted to make surface-to-surface contact with the tubing adjacent the coupling throughout substantially the entire circumference of the tubing, and preferably also throughout an appreciable distance lengthwise of the tubing. The resilient means will have a normal contracted position in which it forms a threat for at least part of its length of lesser size than the tubing, and from. such :position the structure can be expanded to j co'nforrn to the size of the tubing. The throat will have a different contour in its contracted and expanded posi- "tions, and in order that the structure may make surfa'ce to 'surface contact circumferentially with the tubing the contour of the throat is deter- "min'ed'aicofding to the. expanded position of the structiire.

V The invention possesses other objects and featu'res'o'i advantage, some of which, with the foregoing, will be set forthin the following description of the' pteierredembodiments oi my invention which are illu s'trat'd i'n the-drawing accompariyirig and forining pants the specification it is to be understood that-"I do notdimitmyself to the showing 'made by the said drawing E'and descriptionfas fmay adopt variations of thepr'eferred embodimentswithin the scope of my invention ass-e1; fo'rth in the claims.

Referring to the drawing: Figure 1 is a Juneau-21mm, me'dial sectional "-view 'ofa portion f ac pl-in'g membe'r having stress-'-"distributiiog means embodying the principles of the -present i'iveiitio'n cooperatively disposed thereupon. -A -portion of the "tube upon which *the coupling me-ni-ber is intended to 'be positioned is shown in positio n to be thrustfthereinto; and the stress-"distributing elements are shown in "the pos'itio'ns assumed thereby before engagement upon thetube.

' Figure *2 is' aview similar to Fig. "1, but showing th'eiparts ih the respective positions assumed thereby wh n the tubingand coupling "members are disposed in -'asseinbled,' operative relation.

Figure '3 I is i an end-view of the coupling mem- -ber'-tak'en" on the line 3-3 o'f "Figure -1, but on a somewhat smaller scale.

Figure '4 "is a transverse section taken on the line 4:4 of-Figure '2.

Figure "5 1 is an enlarged inore or le'ssdiagrammane explanatory .viewtc' make clear the' reas'on for the circumferential curvature of "'the throat in theembo'diments of the invention shown in "Figures 1' to t; and further-illustrating the effect of employing a 'diiierent'curvature for thethroat.

Figure *6 I is a' 'half longitudinal 'sectionalview of a conventiona1?inverted fiared 'type o'fductile tubingi'cou'pling' 'showing iny improved st'r essthe nut memberof 'a 'coupling of: the well known V "compression type) r r Figure' is a viewsimilar to-Figure 6, but'showing" the stress-distributing "means formed as a portion of the'hut meinb'er of the flared tube-ty-'pe of coupling. I g V Figure-93s anoth'er'view similar to Figure "6, butshowing thest'ress' distributing means formed standard as aiportion'of a nut member of a coupli'rig ofthe icompression ring =t-ype.

but s'ho'w'ing thestres's di'stributiiig means formed a nut me" 'b'r of f a coupling-of the as a prpionio as'01carer-ring type. V

, ing type.

Figure 11 is another view similar to Figure 6, butshowing the stress-distributing means formed as'a part of a separate sleeve in a coupling of the .fcomp'ress'ion type. 'L U f Figure 12 is another View similar to Figure 6, but showing the stress-distributing means of the present invention formed integrally with the sleeve member of a'coupling of the flared tubef ype.

Figure 13 is another view'similar to Figure 6, butshowing the stress-distributing means of the present invention formed integrally with the separable sleeve of a coupling of the soldered By referring first to Figures 1 and 2, the particulars of the flexible, stress-distributing means bridging the juncture of a coupling and the tubing to which it is attached will first be described, after which the manner of application of the stress-distributing means to different types of conventional coupling construction will be illustrated by several examples.

The resilient, stress-distributing means of the present invention is indicated in its entirety at 50, and comprises a body portion 5|, which, as will be described more fully hereinafter, preferably constitutes a portion of the coupling with which the stress-distributing means is to cooperate. Consequently, it is preferred that the distributing means, be constructed of the same material as that of which the remainder of the coupling member by which it is carried is formed, the principal requirement as far as selection of the material is concerned, being that it possesses a material degree of inherent resilience, inasmuch asthis is a feature contributing to the theory of operation of my invention. In most cases, therefore, the material of which the device is constructed will probably most frequently be brass, inasmuch as that is the material commonly em ployed for the construction of couplings of the type here under discussion, and this metal is altogether satisfactory for the purposes of the present invention, having an ample degree of resilience to meet the requirements to be described hereinbelow.

There is a bore 52 completely through the resilient means 50. From the body part 5! there extends a portion 55 having two tapers, one on the outside 53 and the other on the inside 54 in the bore 52. The outside taper 53 graduates the outside diameter of the tapered portion 55 from som maximum value near the body part 5| to some minimum value near the outer end of the tapered portion 55 at point 56.

The inside taper 54 gradualy diminishes the inside diameter of bore 52 from some maximum value at point 51 adjacent the body on said bore to some minimum value away from body part 5| at point 58 adjacent the outer end of the tapered portion 55. The tapered portion is cut by a plurality of longitudinal, radial slots 59 which extend from the extreme outer end of the tapered portion 55 for a material distance toward the body part 5|. The slots 59 may extend either to or beyond the inward end of the outside taper 53 into the body part 5| The slots '59 preferably extend beyond the inward end 51 of the inside taper 54 in the bore 52 for a material distance into the untapered part of the bore 52 inward of point 51 on said bore and into the body part 5!. Between the slots 59 the split parts of the tapered portion 55 form flexible extensions 64 which are integral with and extend from the body part 5l."- Thus the principal parts of the resilient However, excellent results have been 6 means 50 are the body part 5[ and the flexible extensions '64 having the outwardly convergent bore 52 therethrough. The base. 65 of slots59 i often referred to as the root" of flexible extensionsl64. T he natural resiliency of the material of which the device is formed allows the flexible extensions 64 a certain amount of elastic radial flexure. The exact number of slots is determined by the desired degree of flexibility of the flexible extensions 64 consonant with the thickness of the tapered portion 55 as determined by internal taper 54 and external taper 53. It is apparent, therefore, that by selecting the proper number of slots 59 for a stress-distributor of given thickness wall, a nice balance may be assured for the several factors which contribute to the operation of the device.

A circumferential lip 66 extends uniformly around the outer ends of flexible extensions 64 and is cut by slots 59. The bore 52 extending through the lip 65 is reamed out to present a tapered throatfil at the extreme outer end of the extensions 54. The maximum outside diameter of the tapered throat 67 is slightly greater than the maximum inside diameter of the bore 52. inwardly from point 57 on said bore' so as to facilitate assembling the device upon the end of tubing 58 with which it is intended to cooperate. The tube 6.8 having an outside diametera little less. than the maximum inside diameter of bore 52 can be placed in the tapered throat 61 in axial alignment with the resilient means 50. Forcing the tube 63 against the tapered face of the throat 67 causes the flexible extensions 64 to be flexed radially outward due to their inherent elasticity thereby allowing the tube 68 to enter into bore 52. The elasticity. of the inherently resilient flexible extensions 64 causes them to maintain close circumferential engagement with the enclosed tube 68.v

The external taper 53 and the internal taper 54 of the flexible extension 64 are so designed in view of the particular material used that'trusion of the tube 68 into the bore 52 causes the flexible extensions to flex gradually over theirentire length, i. e., not onlyat some one point. In Figure 2 is shown the relative position of the flexible extensions 64 and the tube 68 when the tube has been forced into the bore 52. The internally tapered portion 54 between points 51 and 58 in the bore should contact tube 68 for substantially the entire length 69 of the bore 52 between the two said points. Optimum results are obtained for tube support if this is so, but excellent results are obtained if it is even partially so supported. The allowable variation of plus or minus 0.002 inch in outside diameter of standard market grades of tube 68 makes uniform contact only approximate. For greatest support good accuracy must be maintained for tube outsidediameter and concentricity as related to bore 52. obtained with relatively loose fits.

The internal taper 54 between points 57 and 58 in the bore 52 is not necessarily straight but i is usually increasingly convergent from point 51 to point 58. The exact nature of this longitudinal curve between 51 and 58 is determined by several factors, among them the resiliency of the material used, the longitudinal shape of exterior taper 53, the desired degree of flexibility, etc.

Due to the circumferential curvature of flexible extensions 64 they are stiffer to radial flexure than they would be if they were flat. However,

if flat they make only tangential contact with ascents the enclosed tube and thus "donotofier "circum- *fireritiall support. Fsuch' types "also cannotfbe made *as'easily-on *al'athe. This "circumferential curvature further "influences the longitudinal "curvature of internal "taper 54 between points :51 and 58. Thegreaterthecircumferential angle 'ofagiven flexibleextension-thestiffer it becomes. For "example, "in a brass "coupling unit for 1a inch ductile copper "tube having three slots "in the resilient means "for 'one type or brass the maximuminside diameter at 'pointE'l was "approximately "0.380 inch 'or 02005 "inch over-size, and the minimum inside "diameter'at :point '58 was apprximately0E360 inch or O'DZOinchimder size (or about 0.010- inch "on a side) The longitudinal-curvature in this case is'veryslight. In a four slotted stress-distributor, the curvature might be .greater for the same 'type of 'brass. However, with different materials and different tube "sizes different values must be used. In an cases the number of slots determines the'angular curvature of both longitudinal and "circumferential curves'of the flexible extension. The greater the number of slots, the'ne'arer'an individual flexible extension approaches flatness, and for a given external taper, "the 3 greater mustbe the internal longitudinal curve between points "51 and '58 to 'afford'the same support. 1

The shape "ofithe longitudinal curve v5 1 between points .51 and "58 ton "bore "52 is "also determined by the desired degree "of support of the enclosed 'tube'a'gainst "fiexure. It has been thoroughly verified 'by "experimentthat to attain the longest life in a fluid conductor, .the graduation of the stiffness along the conductor from the high value in "the coupling down tothe lesser value in the tubing should be asnea'rly uniform .asfpossible, andsuch graduation shoul'd 'bespread out over aslon'g a'section'of "theless stifi'member'as is practical. Excessively long flexible extensions do not "support the tube clear out to the tips .of the extensions. 'A"method'ofielastically"connect A ing "the ends of the flexible extensions with a circularspringaroundthe'outer ends 6f the extensions inward of the lip "has been used with 's'ome'success. 'veryshort flexible extensionscannot be made flexible enough without using too littlemetal-to be practical. Each type of material seems to have 'a different set of optimum values which differ-with difierent bore diameters. 'The circumferential contour or "the contracted portion oflbore 52 definedby theflexible'firigers 64isquite important. Merep'ointor' line engagemerit ofthe flexible extension "64 with the tubing 68'has been foundnot to "be satisfactory. "The contact between-the extensions and thetubing should "be surface-to-sur'face .throughout the transverse 'width'of' the extensions so as taprovidesupport 'for'thetubing substantially throughoutits entire circumference. Itis not the intent "of the inve'ntionto-secure a biting engagement between the extensions'and-thetubing, but merely a pressure contact through'the resiliency ofthe extensions. Through such arrangementthe tubing can be freely"forced tnrough theextensions into the connector and withdrawn lther from without'scarring *or'other'rnutilation, and because of the smooth surface fit the tubing and extnsionsmay "flex laterally without substantial increase in stiffness .ofthe tubing because of the extensions. "Becau'se there is'in effect abearing contact betwee'nitl'ie extensions arid tubing. no restrictioni'is imposed upon .relative longitudinal "sliding "movement between such parts' inci der-it toflateralfiexing. r I

Because extensions are "contracted "in *their normal "condition "as shown in Figure "1 and require spreading when tube 68 is inserted; bore 52 should be specially .shapedsoas tlto conform 'tothe contourof the tubing in the sprea'd' posi- 'tion' of the extensions. 'While it might beasisumed thatthe circumferential "contour "of the tapered throatportion i l-of bore 52 would bethe same in both the contracted .position of the 'Tfin- *gersshown'in Fi'gure Tandin the expandedposition thereof when ithe tubing is inserted "asin Figure'Z, this is "notlthe case. Not only thesiz'e but the contour of the throat'is changedin'cident to spreading. If the throat is circular in contour "cular inthe otheriposition.

Assuming that :the tubing, as iordinarily "the 'cfa'sefis circular, the tapered jportion"64 of *bore 52 with acircular contour in the contracted positionof-the'fingers 641s undesirablebecauseupon expansion of the sizeof the bore upon'in'sertion of the tubing the shape'of'the 'borewouldbecome 'non circular. This is explained bythe fact "that 'the smallerithe'size of the borethe smallerthe radius of curvature. The greater the size of a circle the larger :its radius of curvature and the less abrupt its arc. Hence th contour of the inner surfaces 16f fingers 54'. niustloefor'med with the same 'radius'lo'fcurvature'asthe' tubing, which is'to' sa'y .thatthe b'ore collectively defined hyfthe fingers must be determined by the radiusof the bore in "the expanded position ofthefingers as shown in Figure 2. a 1

In the explanatoryview.ofFigure 5, the Idotte'd inner "circle C represents the diameter of .the smallest portion of the contracted bore at point '53 adjacent its outer .end .as .seen in 'Fi ure'l. The largerlfullline circle Ca-representsthe outsidecontourtoftubing 58 which'lis engage'd'bylthe fingers in their expanded ;position as shown in Figure '2. Ri'represeritsthe radius of curvature of thecontracted borejportion,and R2 represents theradius of curvature of the tubing. It .will'b'e observed th'at'the contour of'fin'gers '64' \in"Figure '5 c onform'tothe "arc of a circle "having a. ra'dius of curvature R1. Withsuch an arrangementthe V "presents too abrupt an..arc when expanded to conform jtoithe contour of .the tubing .with the resultithat merely .the i 1ongitudinaledges .of the fingers tenga'ge"the tubing. It .is the intent of I the present invention 'to avoid suchresultlby forming .thecontou'r ofthe'fingers with-them dius'of curvatureR sothat circumferentially the interior surfaces or the fingers will .each present arcs conforming to'jportions of the circular con- "tour of thef tubing. It will"be' noted that in-Figure 3"withthe fingersin contracted ,po'sitionlthe bore definedi by"the"fingers is of non-circularcontourwhereas "when the fingers are expanded to receive the tubeas'iinlFigure 4'thereis fa .Tfiill surface=to+surface contact between lthe Zfingers andthe'tubing throughout the circumferential 'extento'f the respectiveifingers.

"Informing the "contracted bore defined byl'the 'fi'n'ge'rs'b i it is desirable-to expan'd'the fingers from their. normal contractedpo'sitionas shown in- Figure 1 "to their (tube-engaging .position, and then .to form the -.bore .b-y -a drill of uniform: diameter throughout. its length rather than vvithi-a tapered drill. .If -the--body portion 5| provides arclosefit withsthetubingithessame.drillmay be employedto formthe'bore'52 throughout its entire length. If,'h'owever,lthe portion of the bore in body portion 5| is somewhat'oversize with respect to the size of tubing 68 so as to provide only aloose fit, it is desirableto utilize a drill of smaller size than such portion of the bore in forming the bore portion through the normally convergent fingers 64, it being desirable that the arc of curvature of the inner faces of the fingers be the same as, ,or substantially so, the contour of the tubing. It will be apparent, of course, that just as too small a radius of curvature will result in line contact of the-edges of the fingers with the tubing, too large a radius of curvature for the contour of the fingers will cause the fingers to engage the tubingmerely with'linecontact at some point of their circumferential ex tent intermediate their edges. I

Flexure or bendin of the tube against the flexible extensions causes these extensions to give slightly. This elastic yielding of the resilient means is proportional to the degree of flexure within the limits of the material formingthe resilient means. As in a spring leaf, the tips of the flexible extensions make a slidable contact with the enclosed tube. This slip between the flexible extensions and the enclosed tube makes for springy action not present if the flexible extensions are in any way soldered or otherwise rigidly attached to the enclosed tube. They carry the same yieldable support found in an ordinary leaf spring which would also be relatively less useful if its leaves were soldered or welded together. Thus the flexible extensions add support to the tube graduated outwardly from the coupling without greatly adding to its initial stiffness. Because the circumferential contour of the bore defined by the fingers con forms to the tubing as above explained, a smooth surface-to-surface contact is obtained between the resilient fingers throughout theircircumferential extent as well as throughout their length.

Due to the fact that the device is so constructed that before its engagement upon the tube 68 the bore 52 at the outer end of the flexible extensions 64 is slightly less than the outside diameter of the tube, 68 which it is to receive, after-.thetube has been thrust into-the bore theextensions exert pressure radially inwards against the outer circumferential wall of the tube. The gradual decrease in thickness of the metalconstituting: these extensions and the gradual increasein the rate at which thediameter of the bore 52 decreases as the distance from the body 5l' increases preferably are so proportioned with respect to each other, as well as with respect to. the

particular material employed and the number of slots 59 that the pressure exerted by the fingers,

or extensions 64, is substantially evenly distributed over the entire length of the tube with which the fingers make contact. Moreover, due to the yielding nature of the pressure exerted by the fingers 64, this substantially even distribution of pressure is maintained, even after flexure of the tube has occurred to an extent which causes displacement of one or more of the fingers from the positions thereof indicated in Figure 2..

Therefore, whether the portion of the tube 68 embraced by the fingers 64 remains straight or is bent after its insertion into the device, the fingers 64 continue to give yielding support to the tube, which support is substantially evenly distributed throughout the entire length of the fingers.

, It is this evenly distributed support for a Inatrial length of the ductile tubing immediately the coupling increases, I have caused whatever,

curvature may be imposed upon this portion of the tubing to be developed about a greater radius of curvature than would be the case were the resilient support herein describednot proe vided, with a consequent elongation of the-portion of the tubing wherein the curvature occurs. This, of course, reduces the amount of curvature occurrin at any unit portion of the tubing, with the result that no portion of the tubing has as much stress imposedthereupon, although the total amount ofcurvature is not reduced.

which the tubing is subjected.

Whether stress imposed upon the tubing and of such a nature that it tends to causefracture of the tubing, is the result of flexure orofsustained vibration, or of a combination of these The same is true with respect to vibration "to two actions, the stress-distributing means of the present invention prevents concentration of that stress within such a short length of the tubing that serious strain and fracture thereof would quickly re-sultinstead, my device causes the stress to be distributed over a relatively great length of the tubing, with a consequent reduction in the amount of such stress imposed upon any unitportion of the tubing. It i apparent, therefore, how the device of the present invention serves to prolong the usefullife ofductile tubing: With which it is associated.

One of the important feature ofthepresent invention is that it is applicable to any of the. numerous types of coupling for ductile tubing commonly employed. However, in any case, and Without regard to which type of coupling is employed, the stress-distributing means 50 incorporated therewith in accordance with the principles of the present invention comprises the flexible extensions or finger 64 hereinabove described,

carried by a body portion 5| and having acon vergently tapered bore 52 therethrough. The

several individual couplings illustrated are merely exemplary, inasmuch as it has notbeen attempted to illustrate every possible type of coupling with which the device of the present invention can be incorporated advantageously, but merely to illustrate the manner of its incorporation with a few of the better known types of duc-.

. tile tubing couplings; i p I v In Figures 6 to 10, inclusive, the several types of tubing couplings illustrated all embody'the re- 'silienttress-distributing means 58 of my invention as an integral part of a one-piece clamping member which serves as the means for attaching the tubing to the base part of the coupling.

Describing these various forms of couplings in greater detail, Figure 6 illustrates a coupling of the type known in the trade as the inverted nut type, wherein the body portion 5| of my stress distributing means is formed integrally with the clamping ferrule ill, the resilient extensions or fingers 64 extending from the outer end of the ferrule. vided with threads ll engageable with inter or threads of the base part 12 ofthe coupling. The.

bore 13 of the ferrule is adapted to receive the end of the tubing M therein; 'andthe inner end of the bore 13 is flared, permitting a similarly The other end of the ferrule 10 is pro-.

flared portionflS on.the extreme endof the tubinggto be engagedbetweenthe ferrule andfa comj plementarily formed" conical protection", it on" the basapart't 12 when -theferrule, is tightened into the base part:. Inthis manner, the end of the. tubingis" rigidly attached; to the coupling base partl 'l'2 Withits bore registry and communication with bore ll" of the base part. It will be I understood that" the outer end (not shown). of

the base part 12 will bethreaded, as convention ally, forat'tachment of the assembled coupling spreading the fingers to expand the contracted bore:to" thesize' of'thej tubing; and into the 'clampinthebase part; 12; thje fingers Gflextending from the" ferrule resiliently support cumferentia'l' width andlength. with the periphery of the-tubing against lateral flexure in, the coupling-and against sharp bendingstresse either.

at" the point of. connection of. the tubing and base. part; 12 or at thepointof entry of the tubing into. the outer'en'd', of the ferrule; It: The flexible ex:- tensions 64 in all cases bridge the" juncture oil tubing Miarid' the coupling and regulate theradiusof bending of the tubing transversely to its, axis" at and near" the point of contact of" the. tubingwitnthe coupling, I a

Point 8-3 at thebase-ofthe flared, position '55 of tube'l i is the place where stressconcentrations have been found to. be, greatest; in common forms of couplings, but through the addition, of the auxiliary structure provided under; the: invention thi point is. thoroughlyprotected from all.

stress concentration through the resilient support-- given the tubing by. the, flexible fingers 8'5 on the, outer endofthe. coupling; Gradual flexure of the; tubing is allowed: by the fingersto an increasing" degree in the direction. of thenouer' ends of; the: fingers; servingto' distribute all stress resulting from fi'exure and/or vibration over a material length ofithe: tubing My insteadi of permitting such stress, to. be concentrated at point 83, so that danger of fracture of the tubing mitigated. I I r a Figure- 7 shows an inverted nut type of con-- pling generally similar to Figure 6, but employ ing a modified means for attaching the tubing therein; Such means comprises a tapered? de- 7 formable end 85' onthe inner end of the ferrule 86 initially of the same internal diameter as the mainportion of the ferrule but deformable inwardl'y-[against the tubing 81 to the position shown by engagement with the taperedseat formed by specially curved surface t'iin the con-- plin-g base part 88 Whenthe ferrule is tightened therein. The curvature of seat" 89 is such that the tapered end 85 is collapsed inwardly intosuchtight engagement with the tubing that'the latterisrigidlyand tightly attached to the cou-- pling. As inthecaseof the coupling of Figure 6; v

the flexible and resilientfingers 64 beingcarried by ferrule'86 which is rigidly secured-inbasepart 88 are enabled to afford the desiredresilient' support to the tubing enclosed thereby and distribute any stress resulting from flexure and /or vibrationover sufiicient length of tubing to mitigate danger of tube fracture. c

Figures 8, 9 and showthe older'types of i'external nu coupling-s. Figure 8 shows.

said 7 tubing through smooth s'ufia ce-tosuriace; contactof. inner faces of the fingersithroughout their cirstandard Vfl'ared tube type'wherein the interior means; inferrule" 90 "for flaring and securing the tubing end is similar to that in the internal nut type ofjcouplingofFigure 6;;- Figure shows a standard, compression type incorporating adeformable ring92 which is collapsed inwardlyupon the tubing when ferrule: 91, is; tightened; and,

Figure; 10' shows a; standard: soldered tube type whereina special"; ring 94 issoldered to the; end

of tubing% and compressed between ferrule 96 and coupling base-part 91: Inall of these cases the support-for the tubing'is embodi'edin resilient fingers 64 integral with a ferruleand-functionin in the same manner as in connectionwith; the inverted types of" couplings previously" described regardless of which ofthejthree-types' ftube seal is used. 7

ing; ferrule 1t), an'ditheferrule has bcensecured 7 The principal difference betweenthe embodi s ments of'Figuresllt 12 and 1'31 and thqse'oitithe embodiments previously described isthat. each .01; such subsequent embodiments; instead of emplhY- ing a one-piece ferrule incorporating; the auxile iary resilientstress-distributingmeans as an in; V

teg ral part thereof and serving the-dual function of clamping the" tubing to a coupling base part and al'soproviding the resilient support for the;

tubing according tothe principles of the invention, employ a two-part structure: Suchtwopart structure comprises a sleeve interiorlythreaded for securing connection upon an associated coupling basepart, and a compression ring cooperatively disposed inside the sleeve: to be pressed into clamping engagementwith the tubing and 'carry-ing the stress -distributing means;

The only differencebetween the' forms of cou-J plin-g illustrated in Figures 11 12- and- I3 lies-in the manner of connection'bet'ween the compression ring and the tubing, In Figure 11' the compression ring I01 iscollapsed against the outerwall of tubing H12 when the-threaded sleeve I03 is tightened; thus corresponding closely to th I arrangement employed in the embodiment of Figure T. In Figure 12 engagement of tlrecoupling" with the tubing H11 is obtained by clamp ing the flared end N6 of the tubing" between a V conicali flared: portion M8- at theihne'r'end of compression. ring [09'- and a complementarily I formed extension on" the end of coupling basepart llil through tighteningof sleeve I65 In" the embodiment of Figure 13 the compressionringitakestheior-mcfan annulus M2 soldered or othenwise secured to the end of tubing H 3 in themanner of' Figure I0. Such ring I I2 is clamped against the: coupling base part: I M by the inner end: of clampingring; {1L5 which embraces the tubing: and, which isengaged by a. shoulder l tG on threaded sleeve: H?! which may be tightened on the: base: part. I- I4;

It will be, observed'that'. in each of Figures 11:, 12' and. 13 the: resilient stress distributing' means,

comprising, resilient fingers 64 constructed: and

arranged as explainedrin connectiorrwith: Figures 1 to: 4;,inst'ead of being. formed: integrally with the coupling: baseeengaging threaded sleeve, is: formed upon a. separate ring" which is: disposed: inside that element; and which is adapted to=be pressed, into sealing engagement: either with the tubing or with a. ring? soldered to-the. tubing when the threaded. sleeve; is; tightened; Howevergthe action, of the stressedistributing means: on. the;

tubing iszidenticalcwitlr that obtainedin: the coupling embodimentsiof Figures 61m 10'.

Iclaim:

1. In a connector for ductile tubin adapted-to prevent concentration of stress at. the. point of connection, a' body portionhaving a. tubing receiving bore, a plurality of extensions projecting lengthwise from one end of the body portion and cooperatively arranged to normally form a contracted throat concentric with the bore and of smaller size than the tubing, said extensions being resilient and adapted to be spread apart to expand the throat to the size of the tubing and resiliently engage the tubing when received in the bore of the body portion, the tubing-engaging irmer faces of said resilient extensions conforming in their circumferential contour to the shape of the tubing so as to form an expanded throat fitting the tubing when the extensions-are in their spread position and said inner faces defining a different contour as well as smaller size thanthe tubing in the contracted throat when the extensions are in their relaxed position.

2. In a connector for ductile tubing adapted to prevent concentration of stress at the point of connection, a body portion having a tubingreceiving bore, a plurality of circumferentially arranged, resilient fingers projecting lengthwise; from one end of the body portion and cooperating ends whereby said extension bore is of gradually decreasing size in an outward direction to an extent requiring spreading of the fingers as the tubing is thrust into said bore, each of said resilient fingers being of gradually decreasing thickness in an outward direction whereby the lateral support offered said tubing by said fingers is of gradually diminishing intensity outwardly from the inner ends of the fingers, and the tubeengaging inner faces of the fingers throughout their length each having an arcuate circumferential contour adapted to form a circular bore fitting the circumferential contour of the tubing when the'fingers are in their spread, tube-engaging position.

3. A tubing connector adapted to secure the end of a ductile tubing associated therewith without concentration of stress in the tubing such as may arise from fiexure or vibration at the point of connection, said connector including a base coupling part, a sleeve threadedly engaged with said base part and adapted to receive the tubing end therein, and means actuated when the sleeve is tightened with respect to said base part for establishing a fluid-tight and rigid connection between the tubing end and the connector, and stress-distributing means adapted to bridge the juncture of the tubing and connector including a body portion supported by the sleeve and having a bore receiving the tubing, and a plurality of circumferentially arranged, resilient fingers projecting from the outer end of said body portion and 

